Design and application of functional absorbers

This paper gives an overview of the research at Institute of Acoustics, Tongji University, on functional absorbers and experience acquired in practical applications over the past three decades. Experiments and analysis of the absorption characteristics of three different geometrical forms of functional absorbers, i.e., panels, cubes and tubes, were conducted with different arrangements. The resulting esthetical effects are illustrated with pictures. Several non-fiber materials are used to compose functional absorbers with advantages both in acoustic properties and in architectural features. Cost effectiveness analysis is also given in order to provide design guidelines.     

Fetal Neurobehavioral Development: A Tale of Two Cities.

Longitudinal neurobehavioral development was examined in 237 fetuses of low-risk pregnancies from 2 distinct populations-Baltimore, Maryland, and Lima. Peru-at 20. 24. 28. 32, 36. and 38 weeks gestation. Data were based on digitized Doppler-based fetal heart rate (FHR) and fetal movement (FM). In both groups. FHR declined while variability, episodic accelerations, and FM-FHR coupling increased, with discontinuities evident between 28 and 32 weeks gestation. Fetuses in Lima had higher FHR and lower variability, accelerations, and FM-FHR coupling. Declines in trajectories were typically observed 1 month sooner in Lima, which magnified these disparities. Motor activity differences were less consistent. No sex differences in fetal neurobehaviors were detected. It is concluded that population factors can influence the developmental niche of the fetus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

石英砂在菱苦土磨具中的作用机理

本文利用物质结构与化学键的有关理论对石英砂的菱苦土磨具中的作用机理进行分析，并以实验对分析结果进行验证。结果表明：金刚砂晶体中Si-C共价键的离子性百分数仅为9％，石英晶体中Si-O共价键的离子性百分数为47％，因此，石英与主要以离子键结合的菱苦土结合剂之间有较强的静电作用力，石英与菱苦土的结合力强于金刚砂，可提高菱苦土磨具的耐磨性。     

变母体产品可靠性评估方法

产品在不同阶段的技术状态是有差异的，因此在可靠性评估时不能视为同一母体，其试验数据也不能做简单的累加处理。由于试验次数较少，在进行可靠性评估时，评估值往往低于应达到的实际值。本文将各阶段的可靠性作为一个整体来研究，建立了可靠性增长评估的数学模型，导出了成败型可靠性评估方程，给出了评估方法，该方法充分利用各研制的试验信息，反映了研制产品的可靠性增长过程，为多研制阶段、变母体、试验数据较少的产品可靠性验证，提供了有效的评估途径，同时以产品数据为例计算了应达到的实际可靠性水平，计算结果表明，评估结果与产品应达到的可靠性水平基本相同。     

Functional copolymer of geraniol and acrylonitrile: Synthesis and characterization

The radical copolymerization of acyclic terpene namely geraniol [GER] with acrylonitrile [AN] in DMF at (70 ± 0.1)°C for 1 h, using benzoylperoxide (BPO) as an initiator has been carried out under inert atmosphere of nitrogen. The kinetic expression for reaction is R_p ∝ [BPO]^0.5 [AN]^1.0 [GER]^1.0. The IR spectrum of the copolymer shows bands at 3432 and at 2244 cm^?1 due to ? OH group of GER and ? CN group of AN, respectively. The ¹³C‐NMR spectrum shows peaks at 73–75 δ ppm and 116–120 δ ppm due to ? OH group of GER and ? CN group of AN, respectively. The thermogravimetric analysis and differential scanning calorimetry study shows that copolymer is thermally stable up to 407°C and has glass transition temperatures (T_g) 56°C. The reactivity ratios r₁ (AN) and r₂ (GER) have been calculated as 0.05 and 0.005, respectively. The Alfrey‐Price Q‐e parameter for GER has been calculated as 0.094 and ?2.0, respectively. The molecular weights of the copolymers have been evaluated by gel‐permeation chromatography. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Distinctive Features of Minimization of a Risk Functional in Mass Data Sets

A statistical learning model is considered within the framework of the theory of uniform convergence of frequencies of errors in the case where the convergence is violated as a result of increasing the informativeness of training examples. Drawbacks of nonconstructive refinements of Vapnik-Chervonenkis estimates based on an assumption on the distribution law of violations are shown. A new approach to obtaining constructive estimates for mass data sets is proposed.     

Density functional theory studies of Cu-zeolite de-NOx catalysts

Summary Recent progress in the modelling of exchanged Cu sites and their interactions with small molecules, based on DFT cluster calculations, is briefly reviewed.     

复合功能陶瓷中的晶界渗流模型

在复合陶瓷材料中提出了晶界控制的渗液模，考虑晶界效应对渗流阀值的影响，采用ＭｏｎｔｅＣａｒｌｏ模拟，计算得到三维ＦＣＣ晶格点阵的渗流阀值约为４．５％。该结果与实验数据符合得很好。     

动态交通分配中一类转换率系统的稳定性

在假设交通很拥挤同时交通的转换率与路径费用成正比的前提下，构建了一个动态的转换率模型．为了获取转换率系统的全局渐近稳定，提出了一个普遍适用的Lyapunov函数方法，与此同时通过线性矩阵不等式方法，得到了保证转换率系统全局渐近稳定的充分条件．     

钕玻璃激光放大器反转粒子数的荧光测定法

本文报道了通过测量钕玻璃激光放大器在一定泵浦功率下的荧光波形的方法,获得放大器中反转粒子数密度随时间的变化关系,进而得到反转粒子数密度达到最大值的时刻的测定方法及实验结果。